1. Field of the Invention
The present invention relates to a voice data processing device, particularly to a voice data processing device for at least one of recording and/or reproducing a voice.
2. Description of the Related Art
Recently, a digital voice recording and/or reproducing device (hereinafter called simply "digital voice recorder") for recording and/or reproducing a voice has been developed. When a voice is recorded, the digital voice recorder collects the voice as an analog signal by a microphone or the like. The analog signal is converted to a digital signal which is then stored in a storage medium, for example, an IC memory. When the recorded voice is reproduced, the stored digital voice signal is read out from the storage medium, converted to an analog signal, which is then reproduced as a voice by a speaker or the like. Japanese Laid-Open Patent Application Publication No. Sho 63-259700 discloses a digital voice recorder as described above.
A voice data processing device as the digital voice recorder generally applies to the digitized voice signals a coding technique for efficiently compressing the volume of data for saving the space of the storage medium such as the IC memory.
The voice data processing device uses a digital signal processor (DSP) for highly efficient real time coding and decoding.
When the device is manufactured, a program for the highly efficient coding and decoding or the like to be executed by the digital signal processor is first written in a read only memory (ROM) which is then incorporated in the digital signal processor. However, in the voice data processing device, requirements for voice quality, maximum recording time, and functions are different in accordance with its application, and it has been necessary to produce the devices of different specifications for respective applications. Thus, it has been necessary to distinguish at the initial stage of production the devices of different specifications from each other. Accordingly, the devices have been produced after the number of devices of each type was determined. In such a production system for producing the devices differently in accordance with their specifications, a close marketing research is necessary, and even if the close marketing research is implemented, a large amount of surplus or shortage of the products may occur depending on a market trend. Moreover, the existence of various products may result in high costs for production and inventory control. As a result, the product costs may often be increased.
The program of the digital signal processor in the conventional voice data processing device cannot be written and/or rewritten to change its specifications. Therefore, when a new product having new specifications for voice quality, maximum recording time, functions or the like is introduced to the market, users of the old device have to buy a new one, if they desire the new specifications. It is a problem for users to spend extra expense for updating the product.